Lecithin and lecithin fractionates are staple articles of commerce having a wide range of applications. Generally, lecithin of plant origin is obtained from soybeans by (i) cleaning the soybeans, (ii) crushing the soybeans, (iii) separating the crushed soybeans into soybean oil and soybean meal, and (iv) separating the soybean oil into a degummed soybean oil and lecithin.
Lecithin is a complex mixture of phosphatides, glycolipids, triglycerides, carbohydrates, free fatty acids, proteins, fibers and various other constituents of known and unknown structure. Various methods are known for purifying, modifying and fractionating lecithin to produce products containing enhanced concentrations of one or more of the phosphatides—such as phosphatidyl choline, phosphatidyl ethanol amine, phosphatidyl inositol, phosphatidyl serine and phosphatidic acid.
British patent 412 224 discloses treatment of lecithin with acetone or a mixture of acetone and an alkane solvent to selectively dissolve the triglycerides in the lecithin and thereby leave a phosphatide enriched oil-free insoluble fraction.
British patent 877 031 discloses treatment of lecithin with an alcohol for selectively dissolving phosphatidyl choline relative to other phosphatides in the lecithin and thereby producing a phosphatidyl choline enriched alcohol fraction. German patent 14 94 952 discloses that the phosphatidyl choline selectivity of this process can be improved by using aqueous alcohol, while German Patent 16 92 568 discloses that the phosphatidyl choline selectivity of this process can be improved by adding monoglycerides.
A further purified phosphatidyl choline product can be obtained from such a phosphatidyl choline enriched alcohol fraction by (i) treating the phosphatidyl choline enriched alcohol fraction with an adsorbent—such as aluminum oxide—for selectively adsorbing and removing phosphatidyl ethanol amine from the alcohol fraction (British patent 877 031), (ii) treating the phosphatidyl choline enriched alcohol fraction with acetic acid anhydride to convert acetone insoluble phosphatidyl ethanol amine in the alcohol fraction to acetone soluble acetylphosphatidylamine, followed by treatment of the fraction with acetone for selectively dissolving the acetylphosphatidylamine relative to the phosphatidyl choline and thereby producing a phosphatidyl choline enriched solids fraction (British patents 1 217 846 and 1 350 390), and (iii) treating the phosphatidyl choline enriched alcohol fraction with a bivalent or trivalent metal salt, such as magnesium sulfate, to selectively precipitate phosphatidyl ethanol amine from the alcohol fraction (EP patent 0 090 454).
While generally effective for producing a phosphatide and/or phosphatidyl choline enriched lecithin fraction, these processes involve an excessive number of processing steps and typically produce a low yield of the desired product. Hence, a continuing need exists for a simple and efficient method of selectively extracting individual phosphatides or mixtures of phosphatides from a phosphatide-containing matrix at high yield.